Telegraph alarm system



w. Y. LANG 1 TELEGRAPH ALARM SYSTEM I Filed Sept. 1, 1945 2 She e ts-Sheet 1 iven INVENTOR A W Y LANG 8V n REE..

July 29,1947

July 29, 1947.

w. Y. LANG TELEGRAPH ALARM SYSTEM Filed Sept, 1, 1945 2 Shefcs-Sheet 2 3 9 E in:

.type,

equipped with special facilities operable alterna- Patented July 29, 1947 UNITED STATES PATENT OFFICE TELEGRAPH ALARM SYSTEM Wilmarth Y. Lang, Towaco, J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York 1, 1943,,Serial No. 500,743

Application September 12 Claims.

. 1 .This invention relates in general to trouble alarm signaling circuits adapted for use in teletypewriter communication systems and is particularlyapplicable to carrier current communication systems, unattended telephone repeater stations on metallic lines, unattended pumping stations in a pipe line system, substations on power transmission lines and other unattended stations in similar types of service.

An object of the invention is to record at an attended station or central office trouble that occurs in any one of a plurality of circuits at a distant 'pointor station, and to correct it by .means .of permutation code signals transmitted fromthe attended station or central office According to ,the present invention there is provided at each of several unattended outlying stations ("l) a plurality of permutation signal-coding relays-individually operable in response to the occurrence of a trouble condition, (2) a transmitting rotary distributor of the startstop (3)' a bulletin type of teletypewriter ,tiveiy andselectively to perform printing operations or switchingoperations, the additional iacility, including a printing suppression. feature and a set of selector vane controlled switching contacts for operating a fan circuit, and (4) means responsive to.signals received from the attended central oflice ioroperating the selector vane controlled contacts to perform, by means of the fan circuit, switching operations for correcting trouble conditions suchas the switchinginoispare fuses, spare vacuum tubes and other corrective operations. The occurrence oia trouble condition at anyunattended station results .in the transmission .of motor start signals to ,startthe teletypewriter motors at all stations in i the system. Thereupon the outlying station transmits signals representing the identity of the station, and the identity of the trouble conditions which are recorded at all stations as well as at the central oflice. The outlying station also transmits carriage return andline feed signals to all stationsand to thecentralofiica.

A feature of the invention is the automatic transmission from a distant unattended station or .outlyingpoint, of a series of alarm signals using teletypewriter characters to representthe several types of trouble.

Another feature is the provisionof means to prevent two teletypewriter sending equipments at outlying points from sending signals automatically indicating trouble tothe central ofilce at the same instant.

Another feature is the provision of means for recycling after a predetermined interval and resending of several alarms.

Another feature is the provision of means for startingthe remote unattended station from a central attended point and causing the unattended station to send signals giving the type of trouble present or, ifno type of trouble is present,

when a trouble man is at the unattended station.

.jAnother ieatureis the adaptation to a system herein disclosed of a telegraph printing and switching instrumentality in which the switching: selections are additional to and substantially commensurate with the printing selection neither of which embraces substantially the full possli bility v of the signaling code employed.

A better understanding of the invention may be had from the following description and an companying drawings of which:

,Eig. 1 shows vin part, the equipment in sehematic .at one of the outlying stations connected by means of a linecircuit through a second outlying station to'the central ofiice, and

Fig.2 shows the balance of the equipment in schematic at the first-mentioned outlying statifonf 1 The outlying station wherein the equipment is shown in schematic form in both Figs. 1 and 2,

[is referred to herein as station A and the sec- 0nd outlying station shown herein in diagrammatic form is referred to herein as station B.

Theme of reference characters follows a plan. Thus all relaysshown in each figure have reference characters consisting of numerals and letters, the numerals shown as prefixes corresponding to the number of the figure in whichthe particular relay is located. All other parts of the circuit are designated by numerals only, for instance,.those parts of Fig. 1 are designated with nume TaISbetWeenlOO and 199, those in Fig. 2 are designated with numerals between 200and ,299. wherein the first,,or hundreds, digit designates the figure in which the particular part is found.

i j Referringto Figs. 1 and g, a line circuit. comprising conductors LI and L2 extends from the central office C. 0. shown in diagrammatic form, through an outlying station B to the outlying station A. The equipment at station B is understood herein to be similar tothat at station A. Other outlying stations similar to the station shown in schematic may be had in the system if desired.

The equipment shown in station A is arranged to record four different kinds of trouble in the circuit operation, although any reasonable number of trouble sources may be provided and recorded. To perform these functions there is provided a rotary selector switch comprising terminal banks I83 and IM each having a number of terminals equal in number to the arrangements, or groups, of circuits wherein trouble might occur plus four, the four extra terminals on each of these banks being provided for purposes which will be hereinafter described. Should the switch banks be equipped with more terminals than desired the remaining terminals over the number of circuit groups provided, would be strapped to a ground connection, and the switch upon being operated to its last active terminal, would continue to operate over its grounded terminals to its starting, or normal, position. The rotary selector switch shown in Fig. 1 is arranged for twenty-two terminals. The terminals of bank No. 103 are arranged as follows: Terminal No. l is normal and is always open; terminal No. 2 is connected to the innermost left-hand armature of station call relay I--ASC; each of terminals Nos. 3 to 6 is connected to the left-hand armature of a trouble relay of relays I -AI, I A 2, I-A3 and IAfl; each of terminals Nos. '7 to 20 are shown open although one or more of these terminals may be connected to one or more other trouble relays if provided; terminal No, 21 is connected to the operating circuit for carriage return relay I-CR; and terminal No. 22 is con nected to the operating circuit for line feed relay ILF. Each of the trouble relays is provided for a group of circuits that may be considered as being of one type and therefore each of the trouble relays when operated record a distinct typeof trouble. The terminals of bank I84 are arranged as follows: Terminal No. 1 is connected to the normally open stunt contacts ZIlI terminal No. 2 to the innermost righthand armature of station call relay IASC, the armature being normally closed to its back contact; each of terminals Nos. 3 to 6 is connected to the normally closed back contact and righthand armature of a trouble relay of relays IAI, IA2, IA3 and IA-4; terminals Nos. 7 to 20 are shown connected to ground to permit the brushes of both bank I83 and I9 3 to return to their respective normal positions when the switch banks have more terminals than desired in the particular system; and terminals Nos, 21 and 22 are open. It is assumed that in a full capacity system there will be considerably more than four alarm circuits, shown herein, to be recorded.

Relay IA-SC is the station call relay and a corresponding relay will be furnished for each of the other outlying stations connected to the line, relay IB-SC for station B, relay I-C-SC for station C and so forth. At each station there is a trouble relay for each group of circuits capable of giving an alarm and therefore these relays are provided to indicate trouble when trouble occurs. Of the trouble relays shown at station A, Fig. 1, relay IA--I is connected to record trouble in the fuse alarm arrangement for 4 circuit group Hi5, each conductor I 05I, I 0'52, and so forth, of which, may be connected in turn to the load circuit I03. Likewise relays IA2 and IA3 are connected to record trouble in the vacuum tube circuit IE3! and generator set circuit IE8, respectively. Relay IA4 is provided for another type of trouble not shown.

Associated with the station call and trouble relays at each station are other relays, for example such other relays shown at station A which are relays IA associated with station call relay IASC and relays II, I2, I3 and I& are respectively associated with trouble relays IAI, I-A2, I-A-3 and IA4. Relay I-A, upon operating, sends out to each of the other stations and to the central ofiice during the operation of start-stop rotar distributor I09 through one revolution, a signal in permutation code, corresponding to letter A to indicate that there is trouble at station A. Likewise each of relays I-I, I2, I3 and I-4, upon operating, send out a signal in permutation code, corresponding to the character, usual- 1y 2. numeral, to indicate the particular type of trouble that has occurred. Therefore there is a coding relay in the second-mentioned, 0r upper group, for each of the trouble relays such as re- Start-stop distributor I09 is driven by motor 5 it, through friction clutch III, worm H2, worm gear I 53 and main shaft H4. Start-stop rotary distributor I69 sends permutation code signals on a five-unit basis, but different from the standard start-stop distributor in that the length of stop segment is increased to provide suiiicient time for stepping of the rotary switch comprising banks I03 and I 84 and recycling of start magnet H5. The stepping of the rotary selector switch and recycling of the distributor are effected by means of contact set II 6. Each closure of contact set H6 at the end of each revolution of the distributor causes the rotary selector switch to step each of its brushes II! and H8, hereinafter referred to as wipers, one step under the control of stepping magnet ISTP, the stepping of wiper II? from one terminal to the next, deenergizing a coding relay formerly energized and energizing the next coding relay if trouble is present on the circuit associated with the next coding relay in question. The coding relays control start magnet H5 and when the selected relay of the coding relay group is deenergized mag net H5 becomes released and brush arm H9 is, therefore, stopped by means of armature lever I20 engaging projection I2I on cam I22 which is fixedly mounted on main shaft I I 4.

In Fig. 2 is represented within closure 202 a bulletin, or page, type of teletypewriter such as disclosed in W. Y. Langs United States Patent 2,318,168, issued May 4, 1943. The teletypewriter is equipped with special facilities operable alternatively and selectively to perform printing operations or switching operations. The bulletin, or page, teletypewriter is ordinarily provided with a carriage, or type basket, which moves longitudinally on a cylindrical page-width platen for character spacing, and returns to a beginning-of-line position in response to an appropriate selective condition established by a received "carriage return signal. In addition to the printing mechanism ordinarily provided, the teletypewriter represented within enclosure 202 is also provided with a switching control mechanism (not shown) which comprises a rockable cradle which supports a plurality of pairs of electrical contact th sp cina i the s a e p s ve e q a e Alignedwitheachoi the pairs of electrical contact springs isabell crank, one arm ofwhic h is i r,1,-;op erati ve relation to its associated contact springs andthe otherarm of which is presented in the position occupied by an end portion of its associated selector vane, when the. vane is in ,marking position. U Selectable mechanism is pro- ,vided for causing the cradle which carries the sets .of electricalcontacts to berocked by the function bailof the printer-to cause the pairs .ofcontact .springs to rock theirassociated bell cranks towardtheend of the selector'vane. Those of the selectorvanes that are inmarking position interfere with rotation of the bell cranks and cause .thafurther. motion of the pairs of contacts to resu1t,in .c1osure of. thepaths whereas those of .the selector. vanes that are presented in the spacingv position, do not interfere with the associated .bell cranks and the bell cranks rock idlywithout effecting closure oftheir contacts. Electrical circuits controlled frointhe pairs of contacts establishswitchingconditions. ,The contact pairs controlled. from the selector vanes are, in response to ,a received'signal, open orclosed in a combination 1 corresponding to, the received signal, the closed contact pairs being efiective to operate relays in ,the fan circuit, The relays in the fan circuit, upon operating, extend aground connection over a path ,foroperating a device or instru- .mentality for effecting the desired correction in a .circuit in which trouble exists. In Fig, 2 is and it includes a printing suppressioncontact pair .203, a set of selector vane controlled contact pairs 204 to 298, and a contactpair 209 for connecting, immediately. following the establishment of a combination at contact pairs 204 to 2%, ground I to .alcircuit. extended bymeans of the fan circuit to the. device or instrumentality that when operatedeffectsthedesired correction. Contact pairs ;203 and 20 9 operate on a sequence function such as shift, blank or .a character selected, and are respectively provided to control from the remote central ofiice, .the stoppage of. motor 2I3 and the connecting ground to the circuit .iorcorrecting trouble that exists. For a complete description of a bulletin, or. page, .type of teletypewriter wherein is incorporated the above-mentioned switching control mechanism, may be had by reference to Langs Patent 2,318,168, supra.

- In Fig. 1 of Lang's Patent 2,318,168, supra, the

five contact pairs each comprising spring membels 12 and 19 correspond to selector vane control contact pairs 204 to 2G8 in the present application, contact pair I21 corresponds to printing suppression contact pair 283, and spring memshown part of the switching control mechanism f her contact Hit-corresponds. to contact pair 209, t

the five relays designated I31 and provided for I use in the fan circuit corresponds to relays 2--I,

2-2, 2-3, 2-4 and 2-5. In response to a particular signal these relays of the fan circuit operate in acombination-whereby a circuit is completed to operate a device,;such asstepping'magnet 2.-STP. vMagnet L-STP, uponoperating,

,causes brush 2II'I to move one s tep to its next terminal in bank 2I I of a rotary selector switch, ;which in the case shown herein, connects anew fuse tothe load circuit IIIS. Other stepping mag nets similar to magnet 2- -STP may be provided f or correcting othercircuits in which trouble occurs. Each; of. the other stepping magnets is rat d. napir uit l ss lbra iffem MQin-r bination of operated and unoperated relays in the an, Q circ iit, the different "cbnitinatibnsb ,fected by other particular signals received in the typewriter not when sheath printcr For' a complete description ofjthe telemotorcontrol'mechanism shown d grammatically as in enclosure 2l2,.reference may be has to United States Patent igeorieiy rauted a SQMor tonetaI. on-A'pril' 1a, 1933. lAstheft elejtypewriter motor"2l3 starts and comes'lm Tto speed, contact pairs2l4 and, 215 close dueto the action of centrifugal governor 216 which is The action of a centrifugal governor during operation [is idelscribedin United States Patent 1,860;556,"granted toJ. H. Sole on May 31, 1932. Tha teletypewriter control circuit com rises polarized relay: 2RL 2 which is always connected in the line circuit, relay ZR -l which is connected mounted on the motor shaft, 2 I 1.

in the line circuit during idle p'eriods fonly 'jan'd alarm signals are being transmitted, a delay device 2BR such as a "dash-pot relayh'aving a solenoid, or plunger, in a mercury bath to give it acompar'atively longtime delay characteristic so that it requires a definite time to 16perate with, alternatin current applied continuously, but on short breaks offcurrent'imrnediately recycles to its fully released position, and a tin;- ing device comprising motorZIB, a set of t'chd cams such as cams 2 I 9 and 22B driventby motor 218 through worm 22I,

worm ge r 22 2and shaft erated, prevent repeated transmission er trouble tions except at stated intervals as determi the speed of rotationofthe camwhich ispreferably one revolution injten minutes. "A suitable type A of time dl y relay having slow operate and fast-release characteristics is w'll knownin the art.

as shown. The timing. device servesto ridi- Me'thod of operation .Assu'me that trouble occurs at an outlying point such, asstation A and that the indication ofsuch trouble is caused by an excessive voltage fin cir- .cuit 35-1 which includes fuse I23whereby fuse I23 becomes burned out, Relay l -+A--I is sociated with ,the fuses in circuit group I05 -and therefore when fuse E23 burns out a circuit is [closed for-operating rela I-A I traceable fi'fom groundedbattery I24, bus-bar 1 25, alarm spring H6 in its operated position in engagement with bus-bar I21, conductor l28, through the winding of relay I-.-A-I to ground and relay I-A-I opcrates, Fuse I23 isoi the grasshopper type such as shown in United States Patent 2,148,542, granted to A. E. Dietz on February 28, 1939. The

fuse element I23 ,ho1cls under tension a coiled indicating spring I29 to which a glass bead (I3!) is .attached,.and a flat alarm spring I26. They are mounted on opposite sides of a fibre strip about 1% inch long and inch wide and connected by fuse-element I23, through a'hole in the strip. When the fuse burns out both springs are released. The indicating spring gives a visible signal by the glass bead being out of its normal potact are in the line circuit the line circuit now becom s el n LThef ie c rcuit w h. st pi closed, extends from the positive pole of telegraph battery .at the central ofiice, over conductor L-I,

over conductor L4, through the winding of selector magnet 2-SEL, transmitter contacts 231,

over conductor L5. center ring, brushes and stop segment of rotary distributor I09, over conductor L2, through station E and the teletypewriter equipment at the central office to the negative pole of the telegraph battery. Relay 2R-I, the winding of which is in the line circuit and is normally operated, releases and closes at its armature and contact a circuit traceable from alternating current source 224, through the winding of motor 2I8, conductor 225, armature and contact of relay ZR-I, conductor 226, middle righthand armature and contact of relay IA-SC, conductor I3I to the other side of source 224, and motor 2I8 starts. Motor 2I8 is arranged as hereinbefore stated to operate cam shaft 223 at a speed of one revolution in ten minutes, that is, it rotates slowly through one revolution and then stops. When motor 2I8 starts it rotates cams 2 I9 and 220 through one revolution and contacts 22'! associated with cam 220 close to reclose the line circuit,

The open line condition followed by a closed line condition operates the motor stop mechanism 2 I 2 of the teletypewriter and connects power to the teletypewriter as described in United States Patent 1,904,164, supra. The set of timer cam contacts 221 which close the line circuit also shortcircuit relay 2R--I which remains released, and

the contact and outermost left-hand armature of relay I-A-SC, the contacts which just opened the line circuit. As the teletypewriter motor 2I3 starts and comes up to speed, a set of centrifugal contacts 2I4 and 2I5 close. Contacts 2I4 close a circuit extending from one side of alternating current source 224, conductor 229, contacts 2I4, through the Winding of delay relay 2DR, armature and contact .of relay 2R2, conductor 230, contacts 23I which are closed for the first part of the ten-minute interval wherein cam 2 I9 completes one revolution, conductor 232, outermost right-hand armature and contact of relay IA-80, conductor I3I, back to the other side of source 224, and relay 2DR operates if .current in the line circuit is not interrupted such as would be When teletypewrite signals are being transmitted. The other pair of centrifugal contacts 2I5 effects another closure of the line circuit, the path effecting the closure being parallel to that closed at contacts 221 which are closed for approximately the entire interval of the ten-minute duration of one revolution of .cam 220; that is, while the spring member of contacts 22'! rides over the unindented portion of cam 220. Therefore, as long as motor 2I3 is operating, the line circuit cannot be opened by the repetition of a trouble condition or the occurrence of a new trouble.

When delay relay ZDR operates it connects ground at its armature and contact to a circuit traceable over conductor 235, to terminal No. l of selector switch bank I64 and with selector switch wiper H3 normally in engagement with terminal No. 1 a circuit is extended over the contacts and armature and through the winding of stepping magnet ISTP to grounded battery, and magnet ISTP operates over its buzzing circuit one step to terminal No. 2. Upon reaching terminal No. 2 wiper H8 is connected to a path that extends to the innermost right-hand armature and contact of relay I,-ASC, which at this time is operated and therefore the buzzing circuit for magnet ISTP is not completed and the brush I I8 stops on terminal No. 2. Wiper III, however, which steps in unison with wiper l I8 comes to rest on its associated terminal No. 2 and thereby closes a circuit extending over conductor I33, innermost left-hand armature and contact of relay IAS-C, through the winding of relay I-A of the coding group to grounded battery, to operate relay I A. Relay I -A, upon operating, conditions at its right-hand armature and contacts, the line circuit which at this time is arranged to transmit in conjunction with rotary distributor I09 a combination of current impulses corresponding to the letter A, that is, impulses Nos. 1 and 2 are current or closed and impulses Nos. 3, 4 and 5 are no current or open. Alsorelay IA, upon operating, closes at its left-hand armature and contact an obvious operating circuit for start magnet II 5 which operates and attracts armature I20. The armature, upon being operated, is withdrawn from the projection I2I on cam I22 and the distributor I I4 is driven by motor I I0 through friction clutch I I I, motor I I0 being continuously operating when the start switch of its operating circuit is closed. Brush arm II9 of the distributor is caused to rotate once over its segments and the line circuit is thereby closed as its brush passes over segments Nos. 1 and 2, and opened as it passes over segments Nos. 3, 4 and 5. Brush of arm II9 then comes to rest on the stop segment. At a point shortly before the brush of arm II 9 comes to rest contact IIB on cam I34 is momentarily closed to momentarily operate stepping magnet ISTP. The release of stepping magnet ISTP at this time steps wipers II! and H8 to their respectively associated No. 3 terminals. Relay IA releases and opens the operating circuit for start relay II5 which releases. Wiper III, upon engaging its terminal No. 3, closes a circuit traceable from ground, wiper II! on terminal No. 3, left-hand armature and contact of relay IA-I, through the winding of relay II of the coding group to grounded battery. Relay II operates and closes the operating circuit for start magnet II5 and the brush of rotary distributor arm II9 again starts to rotate over the distributor segments to complete another revolution. This second revolution of the distributor arm causes to be transmitted over the line circuit a signal combination corresponding to the numeral I, segment 1, 2, 3 and 5, in conjunction with the righthand armature and contacts of relay II transmitting current or closed impulses and segment No. 4 transmitting a no current or open impulse. Therefore letter A and No. 1 are transmitted to the central office to indicate that trouble exists at station A, in the first circuit group which comprises circuit I05.

Should trouble occur in the second group of circuits which comprises conductor I 01, relays IA-2 and I-2, in addition to relay I-ASC, would operate, and the signals representing letter A and the number 2 would be transmitted. Likewise should trouble occur in the third group of circuits which comprises conductor I08, relays IA3 and I3, in addition to relay IA-SC, would operate and the signals representing the letter A and the number 3 would be transmitted.

Should trouble occur at any one of the other outlying points, such as station B or C, the signal representing the letter B or C Would be transmitted before the signal representing the number of the cincuit group in which trouble occurs.

9 Near the end of the revolution or distributor arm H9 during which the No. 1 was transmitted to the line circuit; contact H6 is again closed'to momentarily operate steppingmagnet l=-'-STP to cause the wipers HT and H8 to'move to their respective No. 4 terminals; Relay l- A--2 being unoperat'ed at this time has a ground. connection at its right-hand armature and back contact to momentarily operate the" buzzing circuit 'for stepping magnet ESTP and wipers ill and H3 therefore move on to terminals No. 5; Likewise relays l-A-3 and I--A-4 being unoperated at this time the buzzing circuit of magnet l--STP again operates to step wipers Ill and H8 first on to theirNo. 6 terminals and thenon totheir No. '7 terminals. Assume that at station A there are only four circuit groups in-which trouble may occur in which event terminal No. '7 and those succeeding, except the last two, are con nected to ground so that the stepping function of wipers H1 and H8 continues until the brushes reach the next to the last terminal. the last andthe last terminals on bank I83 are respectively connected to relays l--CR and i- LF. Relays lCR, and l-LF, upon operating, cause to be transmitted in conjunction with the segments of distributor ms; signals respectively cor responding to the carriage return and the line feed signal combinations. Upon the re ceipt of these combinations the central office is notified that a complete search of the controlled equipment at the outlying station has been made and remedial measures may then be taken to correct'therecorded troubles in the eventthat these troubles are of a type Whichcanbe corrected from a distant point. The-means for correcting these troubles will be hereinafterdescribed.

As the timing motor ZIB has been in operation since the closure of the contactsof relayZ-Rgl following the operation of the'station call relay I-A-SC it will be noted in the circuit of con tacts 23I on cam 2l9 that the slow to-o-perate relay ZDR. cannot again apply ground to terminal No. 1 on selector switch bank 104 until the 1 timing cams'2l9 and220 have made a complete revolution and "contacts 221 on"cam* 220 open the path which serves during each revolution as a short-circuit around relay "2R,l. 'As-hereinbefore stated it is assumed that the time for the complete revolution of timing cams is of the order of ten minutes. It is practicable; however, to make this time more or'less; depending on the needs of the station and the installation of certain equipment therein. If, in the meantime, the trouble which caused the alarm has been cleared, the timing motorg'upon rotation of-the cams through 360 degrees, stops and thecircuit is in condition for reporting another trouble-call. The timing motor continues to operate until all troubles at the station are corrected.

If at any time including the interval when the timer is preventing arecycl'ing operation on the trouble call, a central" office attendant wishes to check for the condition of the controlled apparatu's with respect to the remedial measures which have been taken, or with respect to other troubles which may have occurred, an upper case sequential combination which consists of three signals transmitted in turn, namely, shift, blank and that corresponding tothe desired station letter, 'is sent from the central "oi'fice. This combination operates and closes momentarily stunt contacts 2M in the desired station teletypewriter. These contacts", upon closing, connect ground to conductor235 which extend W The next to terminal N0. 1 on selector switch bank Hi4 whereby the buzzing circuit of stepping magnet l-STP operates to step-wipers Ill and H8 to their respective No. 1 terminals. The No. 1 terminals are dead except when trouble occurs and the selector switch steps its'wipers l H and l lBaround the complete are sending only carriage return and line feed signals uponcompletion of its search, or moves to those points where there are troubles, sends the code signals for. those troubles, andthen moves to the next to the lastand last terminals which complete circuits for sending carriage return and line feed respectively.

Correction For the correction of certain of the types of troubles, for example, on a carrier. system-for stepping up the gain of an amplifier, cuttinginto the circuit a tube-to replace aburnt-out tube, cutting into the circuit a fuse to replace aburntout fuse and other troubles of the type, there is provided a bank 2H of terminals associated with the selector vanes of. a teletypewriterof the type disclosed in United States Patent-1,904,164, supra, -The means ofselecting these terminals on wiper 2H, cuttingthem into the circuitand operating the brush for establishing connection to these terminals is described inLangs .Patent 2,318,168, supra. As set forth in Langs Patent 2,318,168, the five vane and their..-respectively associated contacts 204 to 208 are, connected to ,a fan circuit and. thus thirty-two combinations of contacts of the fan circuit relay contactsgmay be obtained to control thirty-two separate circuits. In addition to these thirty-twocontactswhich may be selected; it-is also-practicable to incorporate a contact associated with the teletype- Writer of the transfer type, closinglto one side in the letters, or lowercase, position, and to the other side in the figures, or upper case, position. Thus, the number of circuits which can be controlled can be considerably increased. It is desirable-ofcourse, in the selection of switching characters fora circuit of this type to avoid selection of characters which might accidentally cause a false operation due'toraminor failure in the teletypewriter mechanism.- One example of this might be the, combination selected for motor control. Although this combination to stopthe motor must' always .be preceded by a blank signal combination, it is reasonableto assume that due to the faults which may occur in anypieGe-of mechanical apparatus, the sending of this combination, not preceded by a blank signal, might accidentally stop the motor, w a

As a means of correcting the trouble a rotary selector switch 21 I having ten terminals isprovided. Anattendant at thecentral o-fliceor at any attendant station sends the break signal combination for rendering the teletypewritervinoperative in so far as printing and spacing is concerned and then sends a signal combination which is transmitted-to the contacts controlling the fan circuit. As-the circuit is-v closed through the fan circuit, ground is applied to the operating circuit for stepping magnet 2-STP on switch 2 i l. Stepping magnet 2STP operates and steps wiper 211cm its next or second terminal, the seccnd terminal being connected to a path comprising conductors Iil5--2, for insertinglawnew fusein the load circuit. a i

The operating circuit for stepping magnet 2-STP which comprises conductor 236 may be any one of the thirty-two separate circuits obtained through the operation of the relays in the fan circuit. Another one of these thirty-two separate cincuits may be extended to the stepping magnet of a second rotary selector switch similar to switch 2H whereby the second switch in stepping to the second terminal on each of several banks, connects a load circuit to the filament, grid and plate elements of a second vacuum tube, similar to the tube controlling relay |-VAC assuming that tube has burned out and recorded its trouble at the central office. Likewise other of the thirty-two separate circuits may be used for substituting new apparatus for the apparatus that has developed trouble. For example, a second generator set may be substituted in place of the one controlling relay |-GEN.

The fan circuit selected by the attendant at the distant station or central oflice may also serve to connect to a second point on a potentiometer for controlling the output gain of a load circuit. The release magnet of a rotary selector switch having ten terminals arranged in a 90 degree arc and similar to that shown in United States Patent 1,759,652, granted to F. S. Kinkcad on March 10, 1931, could also be controlled by contacts of the fan circuit to facilitate reduction in output gain in those cases wherein the gain is too high. However, in the case of replacement, burnt-out apparatus such as tubes and fuses, when a maintenance attendant visits the unattended station and replaces the burnt-out material, is then returned to their N0. 1 position by manual manipulation.

Preventing simultaneous transmission from unattended stations The means for preventing simultaneous transmission from two or more unattended stations to the central office is under the joint control of delay relay 2BR and cam 2!!! of the timing device. The delay relay as hereinbefore stated requires a definite time to operate with alternating current applied continuously, but on short breaks of current resulting from signal impulses on the line circuit immediately recycles to its fully released position. Assume that the line circuit is seized by a trouble alarm circuit at station A, one of the unattended stations, relay |-A-SC at station A operates and opens at its outermost left-hand armature and contact, the line circuit which also includes the winding of relay ZR-l, and relay 2Rl releases. Relay 2Rl, upon releasing, closes the operating circuit for the timing lcircuit motor 2l8 and the motor operates for an interval of ten minutes, that is, until shaft 223 rotates through one revolution. Immediately after shaft 223 starts torotate, cam 22B closes contacts 221 which remain closed for almost the entire ten minute interval, and the line circuit is again closed to short circuit relay 2R,l and the outermost left-hand armature and contact of relay |--ASC. The opening of the line circuit for a short interval followed by a closed condition closes contacts in the motor control circuit 2I2 to start motor 2 l 3 of the station teletypewriter. When motor 2 I 3 comes up to speed, contacts 2M close a circuit extending from one side of alternating current source 224, conductor 229, through the winding of delay relay ZDR, closed armature and contact of relay ZR-Z, contacts 23l which are now closed, that is, for the first part of the ten minute interval, conductor 232, outermost right-hand armature and contact of relay l-ASC, conductor I31, to the other side of source 224 and delay relay ZDR operates if the alternating current is not interrupted such as would be the case when teletypewriter signals are being transmitted or received. The other pair of centrifugal contacts 2I5 effects another closure of the line circuit over a path that is parallel to the path closed at contacts 221. When delay relay ZDR operates, it connects ground at its armature and contact to a circuit for operating stepping magnet l-STP and the magnet operates to step wipers l I! and H8 to the second contacts on their respective banks I63 and Ill-i.

When relay IASC operated, it conditioned. at its innermost left-hand armature and contact a circuit for operating relay l--A and now when stepping magnet l-STP operates its wiper H"! to the second contact on bank I93, a circuit is thereby completed from ground on wiper H1, through the winding of relay IA to grounded battery and relay lA operates in preparation for transmitting the teletypewriter signal combination for letter A to correspond to station A. Relay l-A, upon operating, closes at its lefthand armature and contact, a circuit for operating start magnet H5 of the rotary distributor hit and the distributor, upon operating, through one revolution, transmits to the line circuit the signal combination for letter A.

Relay 2R2 is arranged to respond to the signal impulses transmitted over the line circuit. Delayed relay ZDR is arranged to release quickly and therefore releases when relay 2R-2 releases in response to the start impulse of the signal combination for letter A. Relay ZDR. does not again operate until the beginning of next succeeding interval of ten minutes duration, that is, it cannot operate twice during the time that the raised portion 234 of cam 2l9 is in engagement with the lower spring of contacts 23! during a single revolution of cam shaft 223.

During the time that the line circuit is under the (control of station A, the corresponding delay relay at each of the other unattended stations, such as station B, is in its released position due to teletypewriter signals being on the line circuit and the teletypewriter motors, corresponding to motor 213, at the other unattended stations are operated but without effect other than recording the characters corresponding to the signals transmitted from station A. Should, at the time signals are being transmitted from station A, a relay corresponding to relay |A-SC at any one of the other unattended stations become operated due to trouble in a circuit at such other station, the timing circuit motor at such other station will operate but also without effect because of the inability of delay relay ZDR to operate at this time, to thereby operate its respectively associated stepping magnet corresponding to stepping magnet l-STP. Therefore, inasmuch as the wipers, corresponding to wipers II! and H8 at such other station do not move oif their respective normal contacts, no signals are transmitted from such other station.

In the event that troubles occur at exactly the same instant on [circuits having corresponding positions in the order of sequence for transmission, at two or more unattended stations, which would be on very rare occasions, the incoming signals at the central oflice would be unintelligible and the central ofiice attendant would take control of the line circuit by transmitting a break signal which stops transmission and operation at the station teletypewriters. A few minutes later, say 5 to 8 minutes after the break signal is transmitted and the line circuit is reclosed, the attendant transmits upper case sequential combinations of signals such as a shift signal followed by,,a,blank signal and a character signal representing any one of the unattended stations such as stations A, B, etc. I 'he upper case sequential signal combination, upon being received at the desired station closes the stunt contacts corresponding to contacts 201 at such station and as the wipers, such as wipers H1 and I I8 at station A, reach their normal positions, the central ofiice attendant is permitt d, as hereinbefore stated, to check the condition of the control an,- paratus at the desired stations, each of the stations, in turn, being selected and those whereat the troubles occur being given the required remedy under the control of the central office attendant.

Should trouble occur at one or more stations. after another station has control of the line circult, each of the stations subsequently developing-atrouble would havetowait until the troubles at the first station were automatically reported to the central office before being able to take control of the line circuit.

What is claimed is:

1. In ,a teletypewriter system for transmitting telegraphic messages, a station, a remote point, a channel interconnecting said station and said remote point, means for transmitting telegraphic messages over said channel, electroresponsive equ pment at s id sta n n a u c ng element operably included therein, a substitute element, means in said equipment automatically p erable when the first mentioned element fails to function, for sending over said channel a permutative code to indicate at said remote point the trouble condition of the first-mentioned element, other means operable when telegraphic message-signals are being transmitted over said channel for withholding the transmission of the trouble indicating signals until a predetermined interval after the message transmission is completed, electroselective means permutatively selectable according to various codes, a teletype- Writer at said remote point, recording means and switching means included in said electroselective means respectively arrangedto be selectively operated as desired, by signalsin various codes incoming over said channel from said teletypewriter, and a selectably operable circuit responsive to the operation of said switching meansfor replacing with said substitute element in operative relation in said station in place, of the firstmentioned element.

2. "In a teletypewriter system fortransmitting telegraphic messages, a plurality of stations, a channel interconnecting said stations,,means at each of said stations for transmitting and receiving telegraphic messages to and from the other of said stations, the receiving means at certain of said stations comprising printing mechanism and switching mechanism with means for selecting either of said mechanisms in response tolselecting signals incoming over said channel from the, other oi-saidstations, groups of circuit arrangements at each of said certain stations,

means at said certain of said stations for automatically identifying trouble conditions in any one of said circuit arrangements at its ownparticular station, other transmitting means at said certain stations automatically operable under the control ,of said identifying means for transmitting signals to'each of said stations to furnish the ea orma i as oi n tur an l c tion of said trouble condition as soon as the trouble occurs, other means operable during the ran m s o a. teleg a c mess o e sai channelgforqqwithhholding the transmission of the trouble indicating signals until a predetermined 'nterval and the message transmission over said channel is completed, and means at said certain stations responsive to signals from the first-mentioned transmitting means at saidother stations for automatically replacin the circuit arrangement in trouble condition at said one partitu a stat n-r h 3 communicat n system comprising a P a it c ou yi g stati s a main t n a channel interconnecting said stations, a printing telegraph instrumentality at each of said Sta tions for intercommunicating over said channel between said stations, means at each of said out lying stations for identifying trouble conditions at its own particular station, other means includ ing a source of permutation code signals under the control of said means for automatically transmitting permutation code signals over said channel, leceiving means included in said instrumentality at said main station and said other outlying stations iorco-nverting said transmitted permutation code signals into characters torecord and indicate the nature and location of said trouble condition, and still other means interchangealoly accessible with said converting means to said channel at each of said outlying stations and responsive to signals transmitted from the instrumentality atsaid main station for automatically eiiecting the necessary correction of said troubie condition at said particular station.

A, communication system comprising a pluralityct outlying stationsamain station, a channel interconnecting said stations, a printing telegraph instrumentality at each of said stations for communication between said stations over said channel, said instrumentality at each of said outlying stations comprisingin addition to the printing mechanism a switching mechanism selectively operative from said instrumentality at said main station, means at each of said outlying stations for identifying any one of a plurality of trouble conditions at its own particular station, other means responsive to said means for automatically transmitting telegraph signals over said channel, receiving means included in each of said instrumentalities for converting and recording signals incoming over said channel to indicate the nature and location of said one trouble condition, and still other means in each of said outlying stations responsive to signals transmittedfrom said main station for selectively operating said switchingmechanism at the instrumentality at the station whereat said one trouble condition occurs to c o rre ct for said one trouble condition.

I 5 1a communication system comprising a main station, outlying stations, 9, channel interconnecting said stations, a plurality of circuit arrangements at each of said outlying stations, a printing telegraph instrumentality at each of said outlying stations, another printing telegraph instrumentality at said main station, means in each of said instrinnentalities for providing communication between said stations, other means provided at each of said outlying stations and arranged to automatically respond, to the occurrence of trouble conditions in any one of said circuit arrangements at its own outlying station, stillother means provided at each of said outlying stations and responsive to the operation of said other means for transmitting permutation code signals indicating the trouble condition and the station at which the condition exists, and means included in said printing telegraph instrumentalities for recording characters representing the signals transmitted, and correcting means at said one station responsive to signals transmitted from the printing telegraph instrumentality at said main stations for correcting said trouble condition in the circuit arrangement at said one outlying station.

6. A teletypewriter system comprising outlying stations, a main station, a normally closed line circuit interconnecting said stations, a teletypewriter at each of said stations for communication between stations over said line circuit, a motor for each of said teletypewriters arranged to operate in response to a break for a brief interval in said normally closed line circuit, a plurality of circuit arrangements at each of said outlying stations, means at each of said outlying stations for automaticall transmitting permutation code signals to the other of said stations whenever a trouble condition exists in any one of said circuit arrangements at its own particular outlying station, normally closed contacts at said outlying station included in said line circuit arranged to be maintained open during the operation of said means, timing cams, a motor arrangement for continuously driving said cams during the time that a trouble condition exists in any one of said circuit arrangements, normally open contacts on one of said cams arranged to reclose said line circuit at said one outlying station for the duration of one revolution of said timing cams whereby a break for a brief interval is effected in said line circuit, normally operated means arranged to release in response to the opening of said normally closed contacts to start the motor arrangement whereby the rotation of said timing cams is started, other normally open contacts on another of said cams arranged to close for an interval of comparatively short duration during each revolution of said cams, a time delay device responsive to the closure of said other normally open contacts only during the time that said teletypewriter motor is operating at high speed to cause said transmitting means to repeat said permutation code signals over said line circuit.

'7. A teletypewriter system comprising outlying stations, a main station, a normally closed line circuit interconnecting said stations, a plurality of circuit arrangements at each of said outlying stations, means at each of said outlying stations for automatically transmitting over said line circuit permutation code signals to the other of said stations whenever a trouble condition exists in any one of said circuit arrangements at its own particular station, a teletypewriter and motor therefor at each of said stations connected in said line circuit for communication purposes, receiving means in said teletypewriter at each of said outlying stations comprising selectable switching means and printing means, both responsive at different times to permutation code signals incoming over said line circuit motor starting means in each of said teletypewriters at said outlying stations responsive to a start signal incoming over said line circuit, said start signal comprising an open condition for a brief interval followed by a closed condition in said line circuit, and selective means at each of said outlying stations responsive to the operation of said switching means for correcting for any trouble condition in a, circuit arrangement at its own particular outlying station.

8. A teletypewriter system comprising outlying stations, a main station, a normally closed lin circuit interconnecting said stations, a plurality of circuit arrangements at each of said outlying stations, means at each of said outlying stations for automatically transmitting over said line circuit permutation code signals to the other of said stations whenever a trouble condition exists in any one of said circuit arrangements at its own particular station, a, teletypewriter and a motor therefor at each of said stations connected in said line circuit for communication purposes, switching means and printing means in said teletypewriter at each of said outlying stations selectable in response to permutation code signals incoming over said line circuit motor starting means in each of said teletypewriters at said outlying station arranged to operate in response to a start signal incoming over said line circuit, said start signal comprising an open condition in said line circuit for a brief interval fol lowed b a closed condition, a fan circuit responsive to the operation of the switching means of the teletypewriter at each said outlying station, an operable device responsive to a selectively operated path controlled by said fan circuit for correcting the trouble condition in said one circuit arrangement.

9. A teletypewriter communication system comprising a plurality of subscribers stations, a central office, a normally energized line circuit interconnecting said stations and said central ofiice, a teletypewriter and a driving motor therefor at each of said stations and said central oflice for communication between said stations and said central office over said line circuit, motor starting means included in each of said teletypewriters and responsive to the operation of a character or function key of any one of said teletypewriters for a slightly prolonged interval of time for starting the motor of its own teletypewriter, a printing mechanism and a switching mechanism included in each of said teletypewriters and arranged to be conditioned for operation interchangeably in response to certain permutation code signals transmitted from any one of said teletypewriters, groups of circuit arranger ments at each of said stations, means at each of said stations for transmitting over said line circuit signals to the other of said stations and said central oflice whenever trouble is encountered by any one of said circuit arrangements, means at each of said stations and said central ofiice for recording the information identifying the circuit arrangement in trouble and the station at which said troubled circuit arrangement is located, means in each of said teletypewriters for disabling the printing mechanism and causing said switching mechanism to be accessible to signals incoming over said line circuit in response to a permutation code signal transmitted from any one of said teletypewriters, a fan circuit having a plurality of paths selectively energized under control of said switching mechanism, a plurality of switching devices respectively controlled by said paths for automatically replacing troubled circuit arrangements at each said stations with operable circuit arrangements.

10. An electrical system comprising a control station and a subsidiary station connected by a transmission channel, a series of elements at said subsidiary station, the first element of the series being adapted to perform a given function in said subsidiary station, means whereby other elements of said series may be substituted, one at a time, for said first element to perform said function, automatic means operated by an inoperative condition of any one of said elements when assigned to perform said function to send pulses to said control station selectively indicative of said fact, means operable under control of said control station, to send signals, means operative selectively under control of said signals to replace said one element with a substitute element of said series, an additional means whereby an inoperative condition of said substitute element may similarly cause to be sent pulses indicative of said fact to said control station, and means whereby said substitute element may be similarly replaced under control of pulses from said control station.

11. An electrical system comprising two or more outlying stations, a main station, a transmission channel interconnecting said stations, a series of elements at each of said outlying stations, a first element of the series at each of said outlying stations being adapted to perform a given function, means whereby other elements of each said series may be substituted, one at a time, for the first element of its own series to perform the given function of its series, automatic means at each of said outlying stations operative by an inoperative condition of any one of the elements of its series assigned to perform its given function to send to said main station pulses indicative of said inoperative condition and the location of said one element, and a slow-acting relay located at each'of said outlying stations and operable at predetermined intervals of fixed duration during the normal, or idle, condition of said transmission channel for preventing simultaneous, and therefore interfering, sending over said channel intelligence indicative of the inoperative condition of elements at more than one of said outlying stations,

12. An electrical system comprising two stations, 3, transmission channel interconnecting said stations, a series of elements at one of said stations, the first element of the series being 18 adapted to perform a given function at said one station, means whereby other elements may be substituted, one at a time, for said first element to perform said function, automatic means operated by an inoperative condition of any one of said elements when assigned to perform said function, to transmit to said other station intelligence indicative of the inoperativeness of said element of said series when said element is substituted for use, means for repeating to said other station, at intervals, transmission of the intelligence so long as said inoperativeness remains, means under control of said other station for seizing said channel of transmission at the completion of any one interval, and means at said one station selectively responsive to signals incoming over said channel of transmission from said other station to substitute for use one of said other elements to perform said function.

WILMARTI-I Y. LANG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,164,324 Harrington July 4, 1939 2,266,826 Stockfeld Dec. 23, 1941 2,207,744 Larson July 16, 1940 1,616,186 Harlos Feb. 1, 1927 1,877,635 Antoniono Sept. 13, 1932 1,895,718 Kleinschmidt Jan. 31, 1933 2,135,295 Stewart Nov, 1, 1938 2,273,383 Snavely Feb, 17, 1942 1,971,686 Kinkead Aug. 28, 1934 1,910,867 Vernam May 23, 1933 2,190,540 Desmond Feb. 13, 1940 2,271,305 Mullerheim Jan. 27, 1942 2,003,047 Henton May 28, 1935 

